Stable hydrodynamic trapping of hydrogel beads for on-chip differentiation analysis of encapsulated stem cells

This paper suggests a microbead-trapping device to distribute hydrogel beads in an array that encapsulate stem cell aggregates. Only facile pipetting of micro-bead suspension into the chip enabled trapping of hydrogel beads in microwell array within a few minutes. External hydrodynamic flow to hold beads was unnecessary because crescent weir at microwell hold the bead firmly. Tight holding of bead allowed strong washing for on-chip fluorescent staining as well as convenient culture media change. This device was applied to on-chip embryoid body (EB) formation and differentiation of mouse embryonic carcinoma (EC) cells. It is able to provide a new tool for studying the effect of chemical cues on the differentiation of stem cells encapsulated in hydrogel beads. The mouse EC cells encapsulated in the beads were cultured in the microfluidic device for 10 days to observe the effect of retinoic acid (RA) on neuronal differentiation as a model case. These experimental results verified the feasibility of long-term culture and immunostaining assay of stem cell differentiation. This device is expected to be useful tool for observing proliferation or interactions of cells in 3D microenvironment.